By prohibited, I don't mean things like writing poor quality questions and answers. I also don't mean some of the more obvious anti-social things that would be prohibited almost anywhere, such as abusive/racist/discriminatory behaviour. One last thing I'm also not looking for is just a big whinging and complaining blog.
What I mean are devious behaviours like using "sock puppet" accounts (as I've recently discovered they are called). There are probably a heap of such practices that I'm not aware of. (I suspect what some others might be, but that would be pure speculation, as a new-comer.)
I've spent a number of years occasionally encountering (as an outsider) a useful nugget of knowledge on Stack Exchange here and there, usually as part of a Google search result. At long last, I decided to contribute... and the experience has been a severe eye-opener.
I can now appreciate that that the SE community has sub-cultures within subcultures. Some (I would like to believe most) are true to the ideals of SE, while others seem seriously into the "gaming" or "social-status" side of it.
Rather than encounter the dirty little secrets of SE a bit at a time, I would rather get it all in a dump. That way, I can avoid getting over one disappointment (and developing a coping strategy) only to encounter another. Then, I can move forward with a better appreciation of what not to bother complaining about, what to just have a thick skin about, etc.
I believe most newcomers would probably benefit, in the long-run (if there is to be a long-run for them), from a fuller appreciation of what SE is really like on the inside. Revealing it to them a bit at a time is just like being slowly poisoned.